The Scientific Method

The Scientific Method

The scientific method: 1) propose a hypothesis (the creative part) 2) use data to test hypothesis/model (the hard work part) a hypothesis/model can never be 'proven', but can be disproved; it's a never-ending quest

Case study: How the scientific method leads to our current understanding of the solar system --- the Geocentric model vs. the Heliocentric model Five important men: Ptolemy (Greek, A.D. 100-170) Copernicus (Polish, 1473-1543) Tycho Brahe (Danish, 1546-1601) Kepler (German, 1571-1630) Galileo (Italian, 1546-1642)

Ptolemy (Greek, A.D. 100-170) Ptolemy improved on an earlier model (Earth + a sphere model) and proposed a 'cosmological model' Earth is at the centre of the universe. all stars All other celestial objects travel around the Earth in different circles (and epicycles). Based on aesthetics and naked eye observations. Predictions accurate to within a few degrees and agree with data available at the time. Used for ~ 1000 years

Ptolemy's epicycles: added to 'explain' the sometimes retrograde motion of the planets on the sky As observations get better, more and more epicylcles have to be added...

Copernicus (Polish, 1473-1543) mathematician,astronomer, physician,classical scholar, translator,cleric,beaurecrat,diplomat,economist... The Revolutions of the Celestial Orbs (1543) Revolution: 1) movement around an axis, rotation 2) complete overthrow of the establishment --- OED What about putting the Sun (that very bright fellow) in the middle? --- the Heliocentric model 1) Sun is centre of the universe 2) Earth, like other planets, rotate around the Sun 3) Earth's rotation gives rise to Sun/star's movement across the sky

However, insists on perfect circles so still need epicycles. No more accurate than the Ptolemaic model.

Tycho Brahe (Danish, 1546-1601) the greatest pre-telescope observer recorded planetary motion accurate to ~ 1 arcminute (1/60 of a degree, best humanly possible) accumulated large data set but no good model discovered a nova (Tycho's supernova) and falsified the notion of 'immutable heaven'

Kepler (German, 1571-1630) Tycho's assistant and protege, 'it may not appear that I (Tycho) have lived in vain' motivated by deciphering God's intelligible plans planets move around the Sun in eccentric orbits empirical Kepler's laws that govern planetary movements (even suggested that there is a force from the Sun that result in the motion Newton's gravity) explained Tycho's data more accurately and more elegantly than Ptolemy's model can

Galileo (Italian, 1546-1642) physicist, mathematician,astronomer, philosopher, 'father of science' First telescopic observation of the heaven -- privileged view of the cosmos see sun-spot, lunar craters... show that the heaven is neither unchangeable, nor untarnished Showed convincingly that Earth was NOT at the center of the universe (the phase of Venus...) Dialogue Concerning the two Chief World Systems (Simplicius vs....) Tried and convicted of heresy by the inquisition. Forced to recant his Copernicanism. Officially forgiven by the Roman Catholic church in 1981.

Galileo's great discoveries... Jupiter has 4 moons and there is 'weather' on Jupiter

Sunspot imperfections on the Sun

Even the Church has evolved... (The Galileo story) is a lesson to the Church... Beware of holding steadfastly to a particular interpretation of Scripture and/or a scientific model... for instance, there are various scientific challenges to the Young-Earth Creationist position. We should hold many... Biblical interpretations loosely. For we will never have all the right answers this side of heaven. --- christiananswers.net

It is rather well tested now that the Sun is at the center of the solar system. But converging to such a theory has been a long journey. Any other competing theories are weeded out not because they are aesthetically inferior, but because they don't agree with observations. --- the scientific method

Francis Bacon (English, 1561-1626) ---- English philosopher ---- father of modern science the observation & experimentation theory -- drawing knowledge from the natural world through observation & experimentation, testing of hypotheses -- such methods connected with the occult trend of alchemy during his time -- this 'inductive' methodology has been the backbone of scientific inquiry ever since, and leads to the tremendously successful 'scientific revolution' Arguments cannot suffice for the discovery of new work, since the subtlety of Nature is many times greater than the subtlety of argument. -- Francis Bacon

The sci ent i f i c met hod: 1) propose a 'scientific' hypothesis/model 'scientific' = one that is testable 2) experiments or further observations a hypothesis/model can never be 'proved', but can be disproved Strictly speaking, there are no 'correct' theory, there are only theories that have not yet been 'disproved' despite numerous experiments/observations 3) it's an unending quest inspiration

Is this a scientific statement? People born between April 21 and May 21 are more persistent and determined than people born at other times of the year. Yes 1 hand up No 2 hands up A scientific statement is one that is falsifiable by observations or experiments.

Is this a scientific statement? There are multiple universes that we can not observe or infer existence of in any way. Yes 1 hand up No 2 hands up A scientific statement is one that is falsifiable by observations or experiments.

Is this a scientific statement? God causes leafs to change color in the Fall. Yes 1 hand up No 2 hands up A scientific statement is one that is falsifiable by observations or experiments.

Is this a scientific statement? God does not cause leafs to change color in the Fall. Yes 1 hand up No 2 hands up A scientific statement is one that is falsifiable by observations or experiments.

A scientific statement can be falsified by experiments or observations. Even if you don't know the answer, knowing that a statement is 'scientific' and falsifiable is important: 1) it's impossible to know all facts, but knowing whether a statement is scientific (falsifiable) is easy. 2) You can then take the attitude of either agreeing with the statement or disagreeing with it, pending on the outcome of relevant experimentation/observation. 3) You don't waste time toying with non-scientific arguments. 1) Astrology: every scientific (falsifiable) statements made has been falsified by detailed studies. 2) More dangerous are statements that are non-falsifiable.

Evolution: University of Michigan survey (2005) 80% Europeans and 78% of Japanese believe that humans evolved from other species. But in the U.S. only 40% of adults believe wholeheartedly in evolution, while 39% called it absolutely false. 1) Evolution is in-consistent with Bible. scientific statement? 2) Human and monkey are so different in looks we could not possibly evolve from them. scientific statement? 3) Animals don't have intelligence. scientific statement?

Scientific Literary You are being trained to become voters and citizens, and to become intelligent decision makers. You need to think scientifically in your daily life. Should we build expensive solar power stations/wind farms or cheaper nuclear stations? Is global warming a real threat for Canada?. or should we focus first on air quality? Should I buy genetically modified food? Should I be more worried about a car accident or a flight disaster? Is universal health insurance damaging the nation's economy? Should we fluorinate our water? Should we allow stem cell research? Should we be against globalization? Should we continue to build the International Space Station?...

Is this a scientific statement? Steven Harper is a worse prime minister than Stephane Dion. Yes 1 hand up No 2 hands up

Example Short Presentations 1) Concepts: Kepler's Laws for Planetary Movements Using Tycho's massive data, Kepler suggested 3 simple rules that govern how planets move around the Sun (1605) 1. Planet orbits in an ellipse w/ Sun at a focus 2. Planet moves faster closer to Sun, and slower further away 3. P2 = a3 This explains... This is significant... --- Kepler laid the foundation for our understanding of gravity (Newton 1687)

2) Astronomy Picture of the Day: Retrograde Motion of Mars May April Dec Mar Nov Oct brightest at Dec/Jan (2008 May 11) Jan Feb Sep Aug

In the geocentric view (Ptolemy ~ 200AD), celestial bodies go around us. Mars moves on a circle. Mars moves along an epicycle on circle.... more epicycles Heaven must be wrong if it disagrees with Ptolemy's theory

In the heliocentric view (Copernicus ~1500AD), we all go around the Sun inner planets move faster relative to outer ones simplest explanation for complicated planetary movements continuously being confirmed by observations